Semiconductor device integrating backside power grid and related integrated circuit and fabrication method

ABSTRACT

A semiconductor device includes a substrate, a dielectric region, a plurality of conductive regions, a first conductive rail and a conductive structure. The dielectric region is situated on the substrate. The plurality of conductive regions are situated on the dielectric region. The first conductive rail is situated within the dielectric region, and is electrically connected to a first conductive region of the plurality of conductive regions. The conductive structure is arranged to penetrate through the substrate and formed under the first conductive rail. The conductive structure is electrically connected to the first conductive rail.

PRIORITY CLAIM AND CROSS-REFERENCE

The present application claims the benefit of U.S. Provisional PatentAppl. No. 62/592,744, filed on Nov. 30, 2017, and U.S. ProvisionalPatent Appl. No. 62/592,922, filed on Nov. 30, 2017, each of which isincorporated herein by reference in its entirety.

BACKGROUND

The semiconductor integrated circuit (IC) industry has experiencedexponential growth. Technological advances in IC materials and designhave produced generations of ICs, where each generation has smaller andmore complex circuits than the previous generation. In the course of ICevolution, functional density (e.g. the number of interconnected devicesper chip area) has generally increased while geometry size (e.g. thesmallest component or line that can be created using a fabricationprocess) has decreased. This scaling down process generally providesbenefits by increasing production efficiency and lowering associatedcosts.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures. It isnoted that, in accordance with the standard practice in the industry,various features are not drawn to scale. In fact, the dimensions of thevarious features may be arbitrarily increased or reduced for clarity ofdiscussion.

FIG. 1A illustrates an isometric view of an exemplary semiconductordevice in accordance with some embodiments.

FIG. 1B illustrates an isometric view of a first configuration andarrangement of a dielectric region within an exemplary semiconductordevice in accordance with some embodiments.

FIG. 1C illustrates an isometric view of a second configuration andarrangement of a dielectric region within an exemplary semiconductordevice in accordance with some embodiments.

FIG. 2A and FIG. 2B illustrate isometric views of a first exemplaryintegrated circuit and a second exemplary integrated circuit,respectively, in accordance with some embodiments.

FIG. 3 is an isometric view of a partially-fabricated semiconductorstructure in accordance with some embodiments.

FIG. 4 is an isometric view of a partially-fabricated semiconductorstructure after gap fill is formed in openings and seed layer structuresare partially removed in accordance with some embodiments.

FIG. 5 is isometric views of a partially-fabricated semiconductorstructure after conductive rails and interlayer dielectric fills areformed in accordance with some embodiments.

FIG. 6 is an isometric view of a partially-fabricated semiconductorstructure after etching back the ILD layer and forming poly gates overthe fins in accordance with some embodiments.

FIG. 7 is an isometric view of a partially-fabricated semiconductorstructure after opening a trench in the partially-etched ILD to exposeportions of conductive rails in accordance with some embodiments.

FIG. 8 is an isometric view of a partially-fabricated semiconductorstructure after source/drain terminals are formed in accordance withsome embodiments.

FIG. 9 is an isometric view of a partially-fabricated semiconductorstructure after shallow trench isolation structures are formed inaccordance with some embodiments.

FIG. 10 is an isometric view of a partially-fabricated semiconductorstructure after a gate replacement process in accordance with someembodiments.

FIG. 11 is an isometric view of a partially-fabricated semiconductorstructure after forming metal source/drain contacts in accordance withsome embodiments.

FIG. 12 is an isometric view of a partially-fabricated semiconductorstructure after depositing metal gate material and forming source/draincontacts in accordance with some embodiments.

FIG. 13 is an isometric view of a partially-fabricated semiconductorstructure including BEOL metal wires with self-aligned vias afterdepositing metal gate material(s) and forming source/drain contacts inaccordance with some embodiments.

FIG. 14 is an isometric view of a partially-fabricated semiconductorstructure after forming BEOL metal wires with self-aligned vias inaccordance with some embodiments.

FIG. 15 is an isometric view of a partially-fabricated semiconductorstructure after integrating a backside power grid in accordance withsome embodiments.

FIG. 16 is a flow chart of an exemplar) method for forming a non-planarsemiconductor device in accordance with some embodiments.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, orexamples, for implementing different features of the provided subjectmatter. Specific examples of components and arrangements are describedbelow to simplify the present disclosure. These are, of course, merelyexamples and are not intended to be limiting. For example, the formationof a first feature over or on a second feature in the description thatfollows may include embodiments in which the first and second featuresare formed in direct contact, and may also include embodiments in whichadditional features may be formed between the first and second features,such that the first and second features may not be in direct contact. Inaddition, the present disclosure may repeat reference numerals and/orletters in the various examples. This repetition is for the purpose ofsimplicity and clarity and does not in itself dictate a relationshipbetween the various embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. The apparatus may be otherwise oriented (rotated 90 degreesor at other orientations) and the spatially relative descriptors usedherein may likewise be interpreted accordingly.

The present disclosure describes exemplary semiconductor devices, suchas fin field-effect transistors (finFETs), having one or more conductiverails which may be situated on a semiconductor substrate andelectrically connected to one or more conductive structures penetratingthrough the semiconductor substrate, and describes exemplary methods forfabricating these semiconductor devices. In some situations, the one ormore conductive rails may be electrically connected to source regions,gate regions and/or drain regions of these semiconductor devices, andthe one or more conductive rails may be utilized to connect the sourceregions, gate regions and/or drain regions of these semiconductordevices to one or more power grids situated under the semiconductorsubstrate through the one or more conductive structures. In somesituations, one or more first metal wires each extending in a firstdirection may be situated above and electrically connected to the sourceregions, gate regions and/or drain regions of these semiconductordevices, and one or more second metal wires each extending in a seconddirection different from the first direction may be situated above theone or more first metal wires and electrically connected to the one ormore first metal wires through one or more conductive through vias suchas one or more self-aligned vias.

FIG. 1A illustrates an isometric view of an exemplary semiconductordevice according to an embodiment of the present disclosure. In theembodiment shown in FIG. 1A, the semiconductor device 100 includes asubstrate structure layer 101, a transistor structure layer 103, abackside structure layer 105 and a conductive interconnect structurelayer 107 disposed one over another.

In the present embodiment, the substrate structure layer 101 includes asubstrate 102 and a conductive structure 118 penetrating through thesubstrate 102 to provide electrical connection between a first side anda second side, opposite the first side, of the substrate 102. Forillustration purposes, the first side of the substrate 102, on which thetransistor structure layer 103 is formed, is referred to herein as afront side of the substrate 102 or a front side of the semiconductordevice 100; the second side of the substrate 102, on which the backsidestructure layer 105 is disposed, is referred to herein as a backside ofthe substrate 102 or a backside of the semiconductor device 100.

As to be described in more detail below, a portion of the substrate 102can be removed through a patterning process, such as a dry etch or a wetetch, during fabrication to expose the transistor structure layer 103.Thereafter, a conductive material can fill the portion of the substrate102 to form the conductive structure 118. In some embodiments, theconductive structure 118 can include a conductive through-substrate viasuch as a through-silicon via (TSV) and/or a trench-typethrough-substrate via (e.g. a through-silicon trench (TST)).

In the embodiment illustrated in FIG. 1A, the transistor structure layer103, disposed on the substrate structure layer 101, includes a finstructure 104, a plurality of conductive regions, a dielectric region112, and a plurality of conductive rails 114 and 116. In somesituations, the conductive regions may comprise a plurality of terminalregions such as a source region 106, a gate region 108 and a drainregion 110. The fin structure 104, the source region 106, the gateregion 108 and the drain region 110 may be configured to form a finfield-effect transistor (finFET). However, those skilled in the relevantart will recognize the finFET can include other regions, such as adielectric region (or an isolation region) 120 to provide some examples,without departing from the spirit and scope of the present disclosure.In addition, the configuration and arrangements of the fin structure104, the source region 106, the gate region 108, and the drain region110 as illustrated M FIG. 1A are for illustrative purposes only. Thoseskilled in the relevant art will recognize other configuration andarrangements for the fin structure 104, the source region 106, the gateregion 108, and the drain region 110 are possible without departing fromthe spirit and scope of the present disclosure.

For illustrative purposes, the description that follows describes thesemiconductor device 100 in terms of a finFET. Those skilled in therelevant art will recognize the semiconductor device 100 can be othernon-planar semiconductor devices as well as planar semiconductor deviceswithout departing from the spirit and scope of the present disclosure.

As illustrated in FIG. 1A, the fin structure 104, the source region 106,the gate region 108, the drain region 110, the dielectric region 112(also referred to as an interlayer dielectric (ILD) region), and theconductive rails 114 and 116 are situated on the substrate 102. The finstructure 104 protrudes from the substrate 102 and the dielectric region112, and passes through the gate region 108 between the source region106 and the drain region 110. Although the finFET shown in FIG. 1Aincludes one fin structure 104, those skilled in the relevant art willrecognize the finFET can include more than one fin structure withoutdeparting from the spirit and scope of the present disclosure.

The source region 106, the gate region 108, and the drain region 110 aresituated on the dielectric region 112 with the fin structure 104traversing through the dielectric region 112 onto the semiconductorsubstrate 102. Although not illustrated in FIG. 1A, other dielectricregions can be situated between the semiconductor substrate 102 and thedielectric region 112 as will be recognized by those skilled in therelevant art without departing from the spirit and scope of the presentdisclosure.

The conductive rails 114 and 116 are situated within the dielectricregion 112, and traverse the semiconductor substrate 102 between thesource region 106 and the drain region 110. The conductive rail 114faces a first sidewall of the fin structure 104, and the conductive rail116 faces a second sidewall of the fin structure 104. In somesituations, the conductive rails 114 and 116 are situated to be parallelto the fin structure 104. However, those skilled in the relevant artwill recognize the conductive rails 114 and 116 can be situated to beperpendicular to the fin structure 104 without departing from the spiritand scope of the present disclosure. In this situation, the conductiverails 114 and 116 traverse through the fin structure 104. Additionally,the number of conductive rails can differ depending upon applicationwithout departing from the spirit and scope of the present disclosure.For example, in some situations, the semiconductor device 100 may haveone or more than two conductive rails.

In some embodiments, the dielectric region 112 can be arranged toisolate the source region 106, the gate region 108, and/or the drainregion 110 from the conductive rail 114/116 to prevent electricalconnection between the source region 106, the gate region 108, and/orthe drain region 110 and the conductive rail 114/116. Refer to FIG. 1B,which illustrates an isometric view of a first configuration of adielectric region within an exemplary semiconductor device according toan exemplary embodiment of the present disclosure. A conductive rail114.1 and a dielectric region 112.1 as illustrated in FIG. 1B canrepresent exemplary embodiments of the conductive rails 114/116 and thedielectric region 112 as described above in FIG. 1A respectively. Aconductive region 105.1 as illustrated in FIG. 1B can represent anexemplary embodiment of the source region 106, the gate region 108,and/or and the drain region 110 as described above in FIG. 1A. Asubstrate 102.1 and a conductive structure 118.1 as illustrated in FIG.1B can represent an exemplary embodiment of the substrate 102 and theconductive structure 118 as described above in FIG. 1A. In the exemplaryembodiment illustrated in FIG. 1B, the dielectric region 112.1 isarranged to prevent electrical connection between the conductive rail114.1 and the conductive region 105.1.

In some embodiments, the source region 106, the gate region 108, and/orthe drain region 110 illustrated in FIG. 1A can be electricallyconnected to the conductive rail 114/116 to provide electricalconnection between the source region 106, the gate region 108, and/orthe drain region 110 and the conductive rail 114/116. Refer to FIG. 1C,which illustrates an isometric view of a second configuration of adielectric region within an exemplary semiconductor device according toan exemplary embodiment of the present disclosure. A conductive rail114.2 and a dielectric region 112.2 as illustrated in FIG. 1C canrepresent exemplary embodiments of the conductive rails 114/116 and thedielectric region 112 as described above in FIG. 1A respectively. Aconductive region 105.2 as illustrated in FIG. 1C can represent anexemplary embodiment of the source region 106, the gate region 108,and/or and the drain region 110 as described above in FIG. 1A. Asubstrate 102.2 and a conductive structure 118.2 as illustrated in FIG.1C can represent an exemplary embodiment of the substrate 102 and theconductive structure 118 as described above in FIG. 1A. In the exemplaryembodiment illustrated in FIG. 1C, the conductive rail 114.2 can beelectrically connected to the conductive region 105.2 to provideelectrical connection between the conductive rail 114.2 and theconductive region 105.2. The conductive rail 114.2 is sufficientlyexposed within the dielectric region 112.2 to electrically connect tothe conductive region 105.2 to provide the electrical connection.

As to be described in more detail below, a portion of the dielectricregion 112.2 can be removed through a patterning process, such as a dryetch or a wet etch to provide some examples, during fabrication toexpose the portion of the dielectric region 112.2. Thereafter, theconductive region 105.2 can be deposited onto the portion of thedielectric region 112.2 through deposition where material is grown,coated, or otherwise transferred. In an exemplary embodiment, a heightof the conductive region 105.2 as illustrated in FIG. 1C (labeled H2)can be greater than a height of the conductive region 105.1 asillustrated in FIG. 1B (labeled H1). In this exemplary embodiment, thisdifference in height between the conductive region 105.1 and theconductive region 105.2 results from removing sufficient portions of thedielectric region 112.2 to expose the conductive rail 114.2 to allow theelectrical connection between the conductive rail 114.2 and theconductive region 105.2.

Referring to FIG. 1A again, at least one of the conductive rails 114 and116 can be electrically and/or mechanically connected to otherconductive rails of one or more other finFETs to form an interconnectednetwork of conductive rails. This interconnected network of conductiverails can be used to electrically connect various gate, source, and/ordrain regions of these finFETs to form one or more integrated circuits.These integrated circuits can include basic logical gates, such aslogical AND gates, logical OR gates, logical XOR gates, logical XNORgates, or logical NOT gates to provide some examples, as well as othermore complicated logical circuitry as will be apparent to those skilledin the relevant art without departing from the spirit and scope of thepresent disclosure. This interconnected network of conductive railsallows these electrically connections between the various gate, source,and/or drain regions of these finFETs to be made without traversingthrough conventional metal layers which are conventionally available forrouting signals. As such, the interconnected network of conductive railslessens the area in terms of real estate necessary to form the one ormore integrated circuits when compared to using the conventional metallayers to form these electrically connections between the various sourceregions and/or drain regions of these finFETs.

In some embodiments, a portion of the substrate 102 can be removedthrough a patterning process, such as a dry etch or a wet etch toprovide some examples, during fabrication to expose the conductive rails114 and 116. Thereafter, a conductive material can fill the portion ofthe substrate 102 to form the conductive structure 118. As theconductive rail 114/116 has a sufficient length (e.g. along a directionparallel to the fin structure 104), the conductive structure 118 caneasily be aligned with the conductive rail 114/116. In some embodiments,the conductive structure 118 can also be formed under the fin structure104 such that the fin structure 104 contacts the conductive structure118.

In the embodiment illustrated in FIG. 1A, the backside structure layer105, disposed below the substrate structure layer 101, includes aconductor 122. The conductor 122 is situated on the backside of thesubstrate 102, and electrically connected to the conductive structure118. In some embodiments, the conductive structure 118 in the substratestructure layer 101, formed under the conductive rails 114 and 116 inthe transistor structure layer 103, can be electrically connected to atleast one of the conductive rails 114 and 116 to provide electricalconnection between the front side and the backside of the substrate 102.Hence, the conductive structure 118 can provide electrical connectionbetween the conductor 122, situated on the backside of the substrate102, and the conductive rails 114 and 116, situated on the front side ofthe substrate 102. In some embodiments, the conductor 122 can be a powergrid conductor arranged to transmit power for the semiconductor device100. As such, the semiconductor device 100 can be powered by a backsidepower, thereby saving an amount of routing resources used on the frontside of the semiconductor device 100.

In the exemplary embodiment illustrated in FIG. 1A, the conductiveinterconnect structure layer 107 can include a back-end-of-line (BEOL)interconnect structure formed on the front side of the semiconductordevice 100. The conductive interconnect structure layer 107 may includea plurality of metal wires 124, 126 and 128, and a plurality ofdielectric layers 125, 127 and 130. The metal wires 124 and 126 aresituated in the dielectric region (or an isolation region) 120 andextend in a first direction, and the metal wire 128 is situated in thedielectric layer 130 and extends in a second direction different fromthe first direction. By way of example but not limitation, the firstdirection in which the metal wire 124 extends can be parallel to the finstructure 104, and can be perpendicular to the second direction in whichthe metal wire 128 extends. However, those skilled in the relevant artwill recognize the metal wire 124 can extend in a directionperpendicular to the fin structure 104 without departing from the spiritand scope of the present disclosure.

The dielectric layers 125 and 127 are formed on the metal wires 124 and126 respectively. In some situations, a conductive through via 132 canbe formed in the dielectric layer 125 and aligned with the metal wire124 to provide electrical connection between the metal wire 128 and themetal wire 124. By way of example but not limitation, the metal wire 124can be formed by depositing conductive material(s) into a first trenchof the dielectric region 120, and the dielectric layer 125 can bedeposited over the metal wire 124 in the first trench. Next, thedielectric layer 130 is deposited over the dielectric region 120 and thedielectric layer 125, and a second trench is created by etching thedielectric layer 130. The second trench exposes a portion of thedielectric layer 125 and a portion of the dielectric region 120.

As the dielectric layer 125 and the dielectric region 120 can havedifferent etch selectivities, the exposed portion of the dielectricregion 120 would not be etched when the exposed portion of thedielectric layer 125 is etched. This means that the exposed portion ofthe dielectric layer 125 can be selectively etched. Hence, when theexposed portion of the dielectric layer 125 is selectively etched toexpose a portion of the metal wire 124, the resulting via isself-aligned over the portion of the metal wire 124 because of the firstand second trenches. Thereafter, the metal wire 128 and the conductivethrough via 132 are formed by depositing conductive material(s) into theresulting self-aligned via and the second trench of the dielectric layer130. As such, the conductive through via 132, which is aligned with themetal wire 124, is located on the metal wire 124 and below the metalwire 128 to provide electrical connection between the metal wire 124 andthe metal wire 128. Similarly, a conductive through via can be formed inthe dielectric layer 127 and aligned with the metal wire 126 to provideelectrical connection between the metal wire 126 and a metal wire formedabove the dielectric layer 127.

In some embodiments, a distance between conductive paths within asemiconductor device decreases as the device size shrinks, resulting inan increased risk of dielectric breakdowns within the semiconductordevice, such as time dependent dielectric breakdowns (TDDB). Forexample, consider a case where a distance between the metal wire 124 andthe metal wire 126 is very short because of dimension shrinkage in thesemiconductor device 100. When the conductive through via 132 ismisaligned with the metal wire 124 and moves towards the metal wire 126,there would be voltage breakdowns between the conductive through via 132and the metal wire 126 since a distance between the conductive throughvia 132 and the metal wire 126 fails to meet the misalignmenttolerances. In contrast, as the conductive interconnect structure layer107 can include metal wire(s) with self-aligned via(s), the risk ofdielectric breakdowns in the semiconductor device 100 can be greatlyreduced.

Additionally, in the embodiment as illustrated in FIG. 1A, the metalwire 124 is electrically connected to the source region 106 through aconductive through via 134. Hence, the source region 106 is electricallyconnected to the metal wire 128 through the self-aligned conductivethrough via 132. In some embodiments, the source region 106 electricallyconnected to the metal wire 128 may be further electrically connected toa conductive region (e.g. the gate region 108 or the drain region 110)through the conductive rail 114/116. In some embodiments, the sourceregion 106 electrically connected to the metal wire 128 may be isolatedfrom the conductive rail 114/116 by the dielectric region 120. However,those skilled in the relevant art will recognize that other conductiveregions (e.g. a source region and/or a drain region) can be electricallyconnected to BEOL metal wire(s) without departing from the spirit andscope of the present disclosure. For example, in some embodiments, aconductive through via can be formed between the gate region 108 and themetal wire 124 such that the gate region 108 is electrically connectedto the metal wire 128 through the conductive through via 132. In otherembodiments, a conductive through via can be formed between the drainregion 110 and the metal wire 124 such that the drain region 110 iselectrically connected to the metal wire 128 through the conductivethrough via 132.

FIG. 2A illustrates an isometric view of a first exemplary integratedcircuit according to some embodiments of the present disclosure. In theembodiment illustrated in FIG. 2A, a substrate structure layer 211, atransistor structure layer 213 and a backside structure layer 215 of theintegrated circuit 200 can represent embodiments of the substratestructure layer 101, the transistor structure layer 103 and the backsidestructure layer 105 as described above in FIG. 1A.

The substrate structure layer 211 includes a substrate 102.3 and aconductive structure 118.3. The substrate 102.3 can representembodiments of the substrate 102 shown in FIG. 1A, and the conductivestructure 118.3 can represent embodiments of the conductive structure118 shown in FIG. 1A.

The transistor structure layer 213 includes a finFET 202, a finFET 204,a dielectric region 112.3, a conductive rail 114.3 and a conductive rail116.3. The finFETs 202 and 204 can represent exemplary embodiments ofthe finFET as described above in FIG. 1A. As such, a fin structure 104.3can represent an embodiment of the fin structure 104 shown in FIG. 1A; asource region 106.3 of the finFET 202 and a source region 106.4 of thefinFET 204 can represent exemplary embodiments of the source region 106as described above in FIG. 1A; a gate region 108.3 of the finFET 202 anda gate region 108.4 of the finFET 204 can represent exemplaryembodiments of the gate region 108 as described above in FIG. 1A; adrain region 110.3 of the finFET 202 and a drain region 110.4 of thefinFET 204 can represent exemplary embodiments of the drain region 110as described above in FIG. 1A. The drain region 110.3 and the drainregion 110.4 can be characterized as being a common drain region whichis shared between the finFET 202 and the finFET 204. Additionally, thedielectric region 112.3 can represent an embodiment of the dielectricregion 112 shown in FIG. 1A. The conductive rails 114.3 and 116.3 canrepresent embodiments of the conductive rails 114 and 116 shown in FIG.1A.

The finFETs 202 and 204 are situated onto the dielectric region 112.3,which has the conductive rails 114.3 and 116.3 situated within. Thedielectric region 112.3 can be arranged to allow electrical connectionbetween the conductive rails 114.3 and 116.3 and gate, source, and/ordrain regions of the finFETs 202 and 204. In some embodiments, thedielectric region 112.3 can be arranged to prevent the electricalconnection between the conductive rails 114.3 and 116.3 and gate,source, and/or drain regions of the finFETs 202 and 204.

In the present embodiment, the conductive rails 114.3 and 116.3 traversea length of the semiconductor substrate 102.3 in a horizontal directionbetween the source region 106.3 and the source region 106.4. Theconductive rail 114.3 can be electrically connected to the source region106.3 to provide electrical connection between the source region 106.3and the conductive rail 114.3 as described above in FIG. 1C, and can beelectrically connected to the source region 106.4 to provide electricalconnection between the source region 106.4 and the conductive rail 114.3as described above in FIG. 1C. As such, the conductive rail 114.3provides an electrical connection between the source region 106.3 andthe source region 106.4. However, in the exemplary embodimentillustrated in FIG. 2A, the dielectric region 112.3 is arranged toprevent electrical connection between the conductive rail 116.3 and thesource region 106.4 as described above in FIG. 1B. In this situation,the dielectric region 112.3 effectively isolates the conductive rail116.3 from the source region 106.4 to prevent the electrical connectionbetween the conductive rail 116.3 and the source region 106.4.

The backside structure layer 215 includes a conductor 122.3 and aconductor 122.4. The conductors 122.3 and 122.4 can representembodiments of the conductor 122 shown in FIG. 1A. In the presentembodiment, the conductive rails 114.3 and 116.3 are electricallyconnected to the conductor 122.4 through the conductive structure 118.3penetrating the substrate 102.3. Similarly, the conductive rails 114.3and 116.3 can be electrically connected to the conductor 122.3 through aconductive structure penetrating the substrate 102.3 (not shown in FIG.2A). In some embodiments, at least one of the conductors 122.3 and 122.4can be a backside metal pad or a power grid conductor.

The structure of the integrated circuit 200 as illustrated in FIG. 2A isfor exemplary purposes only. Those skilled in the relevant art willrecognize the integrated circuit 200 can include more finFETs arrangedin a substantially similar manner as the finFET 202 and the finFET 204without departing from the spirit and scope of the present disclosure.Additionally or alternatively, in some embodiments, the integratedcircuit 200 can further include a BEOL interconnect structure formedover the transistor structure layer 213, such as the BEOL interconnectstructure in the conductive interconnect structure layer 107 asdescribed in FIG. 1A.

FIG. 2B illustrates an isometric view of a second exemplary integratedcircuit according to some embodiments of the present disclosure. In theembodiment illustrated in FIG. 2B, a substrate structure layer 221, atransistor structure layer 223 and a backside structure layer 225 of theintegrated circuit 201 can represent embodiments of the substratestructure layer 101, the transistor structure layer 103 and the backsidestructure layer 105 as described above in FIG. 1A.

As illustrated in FIG. 2B, the substrate structure layer 221 includesconductive structures 218.1-218.b, b being an integer greater than one.The conductive structures 218.1-218.b can represent embodiments of theconductive structure 118 shown in FIG. 1A.

The transistor structure layer 223 includes finFETs 203.1.1-203.m.n andone or more conductive rails 214.1-214.a, where n and m are integersgreater than one, and a is a positive integer. The finFETs203.1.1-203.m.n can represent exemplary embodiments of the finFET asdescribed above in FIG. 1A, and the one or more conductive rails214.1-214.a can represent exemplary embodiments of the conductive rails114 and 116 shown in FIG. 1A. The finFETs 203.1.1-203.m.n are arrangedin an array of m rows and n columns. However, other arrangements for thefinFETs 203.1.1-203.m.n are possible without departing from the spiritand scope of the present disclosure. In this embodiment, each of the mrows includes one or more conductive rails from among the one or moreconductive rails 214.1-214.a.

The backside structure layer 225 includes conductors 222.1-222.b, whichcan represent embodiments of the conductor 122 shown in FIG. 1A. In thepresent embodiment, the conductive structures 218.1-218.b areelectrically connected to one or more conductive rails from among theone or more conductive rails 214.1 through 214.a, and are electricallyconnected to the conductors 222.1-222.b respectively.

FIGS. 3-12 illustrate isometric views of partially-fabricatedsemiconductor structures where conductive rail structures formed ininterlayer dielectric materials can be used to provide electricalconnection between multiple gate/source/drain terminals of finFET arraysand provide electrical connection between a front side BEOL interconnectstructure and a backside power grid according to exemplary embodimentsof the present disclosure. The description that follows can be used tofabricate a semiconductor device, such as the finFET as described abovein FIG. 1A, and/or an integrated circuit having one or moresemiconductor devices, such as the integrated circuit 200 as describedabove in FIG. 2A and/or the integrated circuit 201 as described above inFIG. 2B to provide some examples. U.S. Patent Application PublicationNos. 2005/0074960 and 2005/0074961, each incorporated herein byreference in their entireties, describe integration of interconnectisolation air gaps into a semiconductor structure.

FIG. 3 is an isometric view of a partially-fabricated semiconductorstructure according to an exemplary embodiment of the presentdisclosure. A partially-fabricated semiconductor structure 300 includesportions of finFETs. As illustrated in FIG. 3, the partially-fabricatedsemiconductor structure 300 includes a substrate 302, fin structures304, hard masks 306, dielectric spacers 308, and seed layer structures310.

In the exemplary embodiment illustrated in FIG. 3, the substrate 302 canbe a silicon substrate. However, those skilled in the relevant art willrecognize the substrate 302 can alternatively be another semiconductor,a compound semiconductor, an alloy semiconductor or combinationsthereof. In an exemplary embodiment, the substrate 302 can be asemiconductor on insulator (SOI). In an exemplary embodiment, thesubstrate 302 can be an epitaxial material.

As illustrated in FIG. 3, the fin structures 304 can include fin-shapedsemiconductor material protruding from the substrate and can be inparallel with each other. The fin structures 304 include active regionswhere one or more transistors are formed. The fin structures 304 caninclude silicon, another elementary semiconductor, a compoundsemiconductor, an alloy semiconductor or combinations thereof. The finstructures 304 can be fabricated using suitable processes includingpatterning and etch processes. The patterning process can includeforming a photoresist layer overlying the substrate (e.g., on a siliconlayer), exposing the resist to a pattern, performing post-exposure bakeprocesses, and developing the resist to form a masking element includingthe resist. The masking element can then be used to protect regions ofthe substrate while an etch process forms recesses into the substrate302, leaving protruding fins. The recesses can be etched using areactive ion etch (RIE) and/or other suitable processes. Numerous othermethods to form the fin structures 304 on the substrate 302 may besuitable. For example, the tin structures 304 can include epitaxialmaterial, in accordance with some embodiments.

The hard masks 306 can be used to pattern, such as by etching, the finstructures 304. The hard masks 306 can also be used protect the finstructures 304 during subsequent processing steps. In an exemplaryembodiment, the hard masks 306 are formed on the top surfaces of the finstructures 304. The hard masks 306 can also be formed between the finstructures 304 and on top surfaces of the substrate 302. The hard masks306 can made of a dielectric material, such as silicon nitride, siliconoxide, silicon carbide, silicon carbide nitride, titanium oxide, othersuitable dielectric material, and/or combinations thereof. In anexemplary embodiment, the hard masks 306 are not formed on the topsurface of the substrate 302 as illustrated in FIG. 3.

As illustrated in FIG. 3, the isolation spacers 308 can partially fillthe recesses between the fin structures 304 and formed on the sidewallsof the fin structures 304. In an exemplary embodiment, the isolationspacers 308 can be made of a dielectric material such as, for example,silicon oxide, spin-on-glass, silicon nitride, silicon carbide, siliconcarbon nitride, silicon oxynitride, fluorine-doped silicate glass (FSG),a low-k dielectric material, other suitable insulating material, and/orcombinations thereof. In an exemplary embodiment, the isolation spacers308 can be formed by blanket depositing an isolation material over theexposed surfaces and using an anisotropic etching process to removehorizontal portions of the deposited isolation layer. The isolationspacers 308 can be deposited by chemical vapor deposition (CVD),plasma-enhanced CVD (PECVD), physical vapor deposition (PVD), atomiclayer deposition (ALD), other suitable processes, and/or combinationsthereof. Other fabrication techniques for the isolation spacers 308and/or the fin structures 304 are possible. The isolation spacers 308can include a multi-layer structure such as, for example, a structurewith one or more liner layers. The isolation spacers 308 can also beformed by depositing an enhanced spacer layer using multi-stepdeposition and treatment process to eliminate voids and seams in thespacer material. In an exemplary embodiment, the isolation spacers 308can be interlayer dielectric material. In an exemplary embodiment, theisolation spacers 308 are formed directly on the substrate 302 and onthe sidewalls of the fin structures 304.

As illustrated in FIG. 3, the seed layer structures 310 are formed onthe sidewalls of isolation spacer 308. In an exemplary embodiment, theseed layer structures 310 can be formed of silicon material such as, forexample, silicon, silicon compounds, titanium nitride (TiN), tungsten,cobalt, other suitable materials, and/or combinations thereof. In anexemplary embodiment, the seed layer structures 310 can have a differentetch selectivity as the isolation spacers 308. In an exemplaryembodiment, the seed layer structures 310 are formed directly on thesubstrate 302 and on the sidewalls of the isolation spacers 308. In anexemplary embodiment, the seed layer structures 310 can be formed byblanket depositing a semiconductor material over the exposed surfaces,patterning the deposited semiconductor material, and using ananisotropic etching process to remove exposed portions of the depositedseed layer material not protected by photoresists. In an exemplaryembodiment, an exemplary patterning process can include forming aphotoresist layer over the exposed surfaces of deposited seed layermaterial, exposing the resist to a mask or reticle having a patternthereon, performing a post-exposure bake process, and developing theresist to form a masking layer. In an exemplary embodiment, the maskinglayer can be hard masks such as, for example, silicon nitride layers,other suitable layers, and/or combinations thereof. Surface areas ofseed layer material that are not protected by the masking layer areetched using, for example, a reactive ion etching (RIE) processes, a wetetching process, other suitable processes, and/or combinations thereof.In an exemplary embodiment, the etching selectivity can be substantiallydifferent between seed layer material and other structures ofpartially-fabricated semiconductor structure 300 by controlling etchingparameters of the etch process such as, for example, etchant gas type,gas flow rate, etching temperature, plasma power, chamber pressure,other suitable parameters, and/or combinations thereof. For example, theetch process can be an RIE process using fluorocarbon gases such as CF₄,fluoroform (CHF₃), octafluoropropane (C₃F₈), other suitable etchantgases, and/or combinations thereof. The etch process can be ananisotropic etch process. Other fabrication techniques for the seedlayer structures 310 are possible. The seed layer structures 310 caninclude a multi-layer structure such as, for example, a structure withone or more liner layers. The length L of the seed layer structures 310,measured along the fin length, can vary based on device needs, forexample, the length of subsequently formed metal drain channels. FIG. 3illustrates the seed layer structures 310 with different lengths L. Asillustrated in FIG. 3, top surfaces of the hard masks 306, the isolationspacers 308, and the seed layer structures 310 can be substantiallycoplanar by performing suitable planarization processes on the topsurfaces of these structures. The planarization process can be, forexample, a chemical mechanical polishing (CMP) process.

FIG. 4 is an isometric view of a partially-fabricated semiconductorstructure after gap fill is formed in openings and seed layer structuresare partially removed according to an exemplary embodiment of thepresent disclosure. Partially-fabricated semiconductor structure 400includes the substrate 302, the fin structures 304, the hard masks 306,the dielectric spacers 308, seed layer structures 410, and gap fillstructures 402.

As illustrated in FIG. 4, the gap fill structures 402 can fill theopenings in the partially-fabricated semiconductor structure 300 asdescribed in FIG. 3 above. The gap fill structures 402 can fill theopenings formed between any adjacent structures such as, for example,between adjacent fin structures 304, between opposing fin structures 304and the seed layer structures 310, between opposing the seed layerstructures 310, and/or other openings between structures. In anexemplary embodiment, the gap fill structures 402 can be made of adielectric material similar to the isolation spacers 308, such as, forexample, silicon oxide, spin-on-glass, silicon nitride, silicon carbide,silicon carbon nitride, silicon oxynitride, FSG, a low-k dielectricmaterial, other suitable insulating material, and/or combinationsthereof. In an exemplary embodiment, the gap fill structures 402 can beformed by blanket depositing a gap fill material over the exposedsurfaces and in the openings and performing a planarization process toremove the excessive gap fill material that is formed over the topsurfaces of the hard masks 306 and the seed layer structures 310 suchthat the top surfaces of partially-fabricated semiconductor structure400 are coplanar. Exemplary planarization processes can include CMPprocesses. The gap fill structures 402 can be deposited by CVD, PECVD,PVD, ALD, other suitable processes, and/or combinations thereof. Otherfabrication techniques for the gap fill structures 402 are possible. Thegap fill structures 402 can include a multi-layer structure such as, forexample, a structure with one or more liner layers. The gap fillstructures 402 can also be formed by depositing an enhanced gap filllayer using multi-step deposition and treatment process to eliminatevoids and seams in the spacer material.

After the gap fill structures 402 are formed, the seed layer structures310 are etched back to form the seed layer structures 410. The seedlayer structures 310 can be etched by any suitable etching processes forexample, an RIE processes, a wet etching process, other suitableprocesses, and/or combinations thereof. In an exemplary embodiment, theetching process can be an anisotropic etching process. In an exemplaryembodiment, the etching selectivity can be substantially differentbetween seed layer material and other structures of thepartially-fabricated semiconductor structure 400 by controlling etchingparameters of the etch process. The etching process can continue until anominal thickness of the partially-fabricated semiconductor structure400 is reached. In an exemplary embodiment, the thickness of the seedlayer structures 410 can be in a range of between about 5 Å to about 15Å (e.g., 5 Å to 15 Å). In an exemplary embodiment, the seed layerstructures 410 can have a thickness of about 10 Å. The thickness of theseed layer structures 410 can be determined by a few factors, includingbut not limited to, the thickness uniformity and impact on conductivity.For example, a reduced seed layer thickness may impact the uniformity ofthe seed layer thickness, while a greater thickness may impact theoverall conductivity of the subsequently formed conductive rails.

FIG. 5 is isometric views of a partially-fabricated semiconductorstructure after conductive rails and interlayer dielectric fills areformed according to an exemplary embodiment of the present disclosure.As illustrated in FIG. 5, partially-fabricated semiconductor structure500 includes the substrate 302, the fin structures 304, the hard masks306, the dielectric spacers 308, the gap fill structures 402, the seedlayer structures 410, conductive rails 502, and dielectric fill 504. Inan exemplary embodiment, the dielectric spacers 308, the gap fillstructures 402, and the dielectric fill 504 can be formed of the samematerial. For simplicity purposes they are combined and illustrated asan interlayer dielectric (ILD) 506 (also referred to as a dielectricregion).

As illustrated in FIG. 5, the conductive rails 502 can be formed on theseed layer structures 410. In an exemplary embodiment, the conductiverails 502 can be formed of any metal materials or conductive materials,such as tungsten, cobalt, copper, aluminum, other suitable materials,and/or combinations thereof. In an exemplary embodiment, the conductiverails 502 can be formed using metal alloys of the above listed material.The top surface of the conductive rails 502 can be a substantiallysmooth surface. The conductive rails 502 can be formed using the seedlayer structures 410 as a seed layer where the growth of the conductiverails 502 is started. For example, the conductive rails 502 can startforming from the top surface of the seed layer structures 410 until anominal thickness of the conductive rail is achieved. In an exemplaryembodiment, the growth of conductive rail material can be completedusing suitable processes such as CVD, electroplating, electrolessplating, other suitable processes, and/or combinations thereof. Forexample, tungsten material can be formed using silicon material as aseed layer. The height of the conductive rails 502 can be in a rangebetween about 0.8 to about 1.2 times the gate pitch of the finFETdevices. In an exemplary embodiment, the width of conductive rails canbe in a range between about 0.8 to about 2.2 times the width of the finstructures 304. In an exemplary embodiment, the pitch of conductiverails (i.e., the distance between centers of adjacent conductive rails)can be in a range between about 0.8 to about 1.2 times the fin pitch ofthe fin structures 304. In an exemplary embodiment, each the conductiverails 502 can have substantially similar widths or heights. In anexemplary embodiment, the widths or heights can be different betweeneach of the conductive rails 502.

After the conductive rails 502 are formed, the dielectric fills 504 areformed over the conductive rails 502 and filling the openings within thegap fill structures 402. In an exemplary embodiment, the dielectricfills 504 can be formed by performing a blanket deposition of dielectricfill material on the structure until the openings within the gap fillstructures 402 are completely filled. A planarization process issubsequently performed to remove the excessive dielectric fill materialand planarize the dielectric fill material until the top surfaces of thedielectric fill material are coplanar with the hard masks 306. After theplanarization process, the planarized dielectric fill material forms thedielectric fills 504. In an exemplary embodiment, the dielectric fills504 can be formed using the same material as dielectric spacers 308 andthe gap fill structures 402. For example, the dielectric fills 504 canbe formed using silicon oxide, spin-on-glass, silicon nitride, siliconcarbide, silicon carbon nitride, silicon oxynitride, FSG, a low-kdielectric material, other suitable insulating material, and/orcombinations thereof. In some situations, the dielectric spacers 308,the gap fill structures 402, and the dielectric fills 504 can be formedusing the same material as illustrated as the ILD 506 for simplicity.

FIG. 6 is an isometric view of a partially-fabricated semiconductorstructure after etching back the ILD layer and forming poly gates overthe fins according to an exemplary embodiment of the present disclosure.Partially-fabricated semiconductor structure 600 includes the substrate302, the fin structures 304, the hard masks 306, the seed layerstructures 410, the conductive rails 502, partially-etched ILD 602, andpoly gate structures 604.

In the exemplary embodiment illustrated in FIG. 6, the ILD 506 frompartially-fabricated semiconductor structure 500 of FIG. 5 is uniformlyetched until a nominal depth is achieved. The etching process can be anisotropic etching process where the etched thickness of the ILD 506 isuniform across the semiconductor structure. The ILD 506 formspartially-etched ILD 602 after the etching process. After the etchingprocess, portions of the fin structures 304 can protrude from the topsurfaces of the partially-etched ILD 602. The amount of the ILD 506removed can depend upon a few factors. First, the protruding portions ofthe fin structures 304 are used to form the active portions of finFETdevices in subsequent fabrication steps. For example, the protrudingportions of the fin structures 304 represent active portions of the finthat are used to form the channel and source/drain regions of the finFETdevices. Therefore, a sufficient height for the fin structures 304 canbe above the top surfaces of partially-etched ILD 602. Second, theconductive rails 502 should remain under partially-etched ILD 602 afterthe etching process without being exposed.

After the partially-etched ILD 602 is formed, the poly gate structures604 can be formed on the exposed surfaces of the fin structures 304including top surfaces and sidewall surfaces not covered by thepartially-etched ILD 602. In an exemplary embodiment, portions of thehard masks 306 can be patterned and removed before depositing the polygate material such that the poly gate structures 604 can form directlyon the top surfaces of the fin structures 304. In an exemplaryembodiment, removing the hard mask layer includes performing a wetchemical process with phosphoric acid (H₃PO₄) that etches siliconnitride. The poly gate structures 604 can be formed by blanketdepositing a semiconductor material and performing patterning andetching processes. The poly gate structures 604 can include a gatedielectric layer, a gate electrode structure, and/or one or moreadditional layers, according to some embodiments. In an exemplaryembodiment, the poly gate structures 604 use polysilicon as the gateelectrode structures. In an exemplary embodiment, the poly gatestructures 604 use amorphous silicon as the gate electrode structure. Inan exemplary embodiment, the poly gate structures 604 can be sacrificialgate structures such as formed in a gate replacement process used toform metal gate structures. In an exemplary embodiment, a hard mask (notshown in FIG. 6) is disposed on a top surface of the poly gatestructures 604. The hard mask can be used to pattern, such as byetching, semiconductor material to form the poly gate structures 604. Inan exemplary embodiment, the hard mask can be made of a dielectricmaterial, such as silicon nitride. In an exemplary embodiment, the polygate pitch (i.e., the distance between centers of adjacent poly gatestructures 604) can be in a range between about 10 nm to about 300 nm.

FIG. 7 is an isometric view of a partially-fabricated semiconductorstructure after opening a trench in the partially-etched ILD to exposeportions of conductive rails according to an exemplary embodiment of thepresent disclosure. Partially-fabricated semiconductor structure 700includes the substrate 302, the fin structures 304, the hard masks 306,the seed layer structures 410, the conductive rails 502, thepartially-etched ILD 602, the poly gate structures 604, and trenches 702formed in the partially-etched ILD 602.

In the exemplary embodiment illustrated in FIG. 7, the trenches 702 areformed between adjacent poly gate structures 604 and in thepartially-etched ILD 602. The trenches 702 are used to expose portionsof one or more of the conductive rails 502 that are formed betweenadjacent poly gate structures 604 such that subsequent structures (e.g.,source/drain contacts and/or gate contacts) can form direct electricalcontact with the conductive rails 502. The specific the conductive rails502 to be exposed depend on circuit designs and can be one or more ofthe conductive rails 502. The fabrication process to expose selectedconductive rails 502 can include patterning and removing portions of thepartially-etched ILD 602 that are formed over the selected conductiverails 502. In an exemplary embodiment, an entire area of thepartially-etched ILD 602 that is surrounded by opposing adjacent finstructures 304 and opposing adjacent poly gate structures 604 is etchedto expose the underlying conductive rails 502. Exposing the entire areadescribed above maximizes contact area to the conductive rails 502 andthus provides the benefit of minimizing contact resistance to theconductive rails 502. In an exemplary embodiment, only portions of thearea are exposed. For example, conductive rail regions 502A and 502B ofthe conductive rails 502 are exposed as illustrated in FIG. 7.Patterning and exposing a portion of the area provides the benefit of agreater tolerance to lithography alignment as it reduces the possibilityof exposing unwanted adjacent areas of the partially-etched ILD 602 incase a misalignment occurs. In an exemplary embodiment, the area exposeddepends on the circuit and device needs and considerations. Thepatterning process can include forming a photoresist layer overlying thestructure (e.g., on the poly gate structures), exposing the resist to apattern, performing post-exposure bake processes, and developing theresist to form a masking element including the resist. Due to the smallfeature size and pitch between adjacent poly gate structures 604, thepatterned photoresist sheet can have sufficient mechanical strength tosuspend between adjacent poly gate structures or hang as a ledge overthe edge of a poly gate structure. After the patterned photoresist isformed, one or more etching processes can be performed to remove theexposed partially-etched ILD 602 to expose the selected underlying theconductive rails 502.

FIG. 8 is an isometric view of a partially-fabricated semiconductorstructure after source/drain terminals are formed according to anexemplary embodiment of the present disclosure. Partially-fabricatedsemiconductor structure 800 includes the substrate 302, the finstructures 304, the seed layer structures 410, the conductive rails 502,the partially-etched ILD 602, the poly gate structures 604, andepitaxial source/drain terminals 802.

In the exemplary embodiment illustrated in FIG. 8, each finFET includesa pair of source/drain terminals. The source and drain terminals areinterchangeable and are formed in, on, and/or surrounding the finstructures 304. A source or drain terminal is formed on one side of apoly gate structure. In an exemplary embodiment, adjacent finFET devicesshare a common source/drain terminal. Channel regions of the finstructures 304 underlie the respective the poly gate structures 604. Oneor more epitaxial source/drain terminals 802 directly contact and areelectrically connected to the exposed conductive rails. For example,epitaxial source/drain terminals 802A and 802B of epitaxial source/drainterminals 802 respectively connects to conductive rail regions 502A and502B. Although only epitaxial source/drain terminals 802A and 802B areshown to be connected in FIG. 8, other source/drain terminals can alsobe connected depending on the design and device needs. Because theconductive rails are formed within the partially-etched ILD 602, theycan electrically connect multiple source/drain terminals withoutoccupying additional device space.

As illustrated in FIG. 8, the epitaxial source/drain terminals 802 canbe formed on active fin structures of the fin structures 304 that areprotruding from the top surface of the partially-etched ILD 602. In anexemplary embodiment, the epitaxial source/drain terminals 802 can beepitaxial source/drains terminals that are formed by growing epitaxiallayers over exposed surfaces of fin 304. In an exemplary embodiment, thehard masks 306 are removed from the top of the fin structures 304 priorto the formation of the epitaxial source/drain terminals 802. In anexemplary embodiment, the fin structures 304 are formed using epitaxialmaterial such as epitaxial silicon, epitaxial silicon germanium (SiGe),gallium arsenide, other suitable materials, and/or combinations thereof.Growing the epitaxy layers on exposed surfaces of the fin structures 304can include performing a pre-clean process to remove the native oxide onthe surface of the fin structures 304. Next, an epitaxy process isperformed to grow the epitaxy layers on the exposed surfaces of the finstructures 304. In an exemplary embodiment, the epitaxy process is anSiGe epitaxy process performed at a temperature between about 400° C.,and about 1000° C. (e.g., between 400° C., and 1000° C.). The epitaxyprocess is a selective process that only grows the epitaxy layer on theexposed surfaces of the active fin structures. The epitaxy process canuse the exposed surfaces of the fin structures 304 as seed layers andthe growth process continues until a nominal size and/or structure ofsource/drain terminals has been reached. An in-situ doping process canalso be performed during the epitaxy process. In an exemplaryembodiment, epitaxial source/drain terminal 802 is a SiGe structure. Inan exemplary embodiment, the epitaxial source/drain terminals 802 can bea silicon structure. In an exemplary embodiment, the thickness of theepitaxial source/drain terminals 802 is between about 10 nm and about 20nm (e.g., between 10 nm and 20 nm). In an exemplary embodiment, theepitaxial source/drain terminals 802 are doped with p-type or n-typedopants during the epitaxy process. For example, the epitaxialsource/drain terminals 802 can be doped with boron (B) during theepitaxy process. The epitaxial source/drain terminals 802 can also takedifferent shapes depending on various factors such as, for example, theepitaxy process condition, the crystalline orientation of active finstructures, and/or other suitable factors. In an exemplary embodiment,the shape of the epitaxial source/drain terminals 802 using epitaxialmaterial have a substantially diamond-shaped cross section. In anexemplary embodiment, top surfaces of the epitaxial source/drainterminals 802 can be recessed below top surfaces of the poly gatestructures 604 as illustrated in FIG. 8. In an exemplary embodiment, thetop surfaces of the epitaxial source/drain terminals 802 aresubstantially coplanar as the top surfaces of the poly gate structures604.

FIG. 9 is an isometric view of a partially-fabricated semiconductorstructure after shallow trench isolation structures are formed accordingto an exemplary embodiment of the present disclosure.Partially-fabricated semiconductor structure 900 includes the substrate302, the fin structures 304, the seed layer structures 410, theconductive rails 502, the partially-etched ILD 602, the poly gatestructures 604, and shallow trench isolation (STI) structures 902.

As illustrated in FIG. 9, the STI structures 902 can be deposited inopenings of the partially-fabricated semiconductor structure 800described above with reference to FIG. 8. The STI structures 902 can beused to provide electrical isolation and mechanical support forsubsequently formed structures. The STI structures 902 can be formedusing dielectric material such as, for example, silicon oxide,spin-on-glass, silicon nitride, silicon oxynitride, FSG, a low-kdielectric material, other suitable insulating material, and/orcombinations thereof. The STI structures 902 can be formed by depositinginsulating dielectric material to fill the openings followed by aplanarization process (e.g., a CMP process). The STI structures 902 canbe deposited by CVD, PECVD, PVD, ALD, other suitable processes, and/orcombinations thereof. Other fabrication techniques for the STIstructures 902 are possible. The STI structures 902 can include amulti-layer structure such as, for example, a structure with one or moreliner layers. The STI structures 902 can also be formed by depositing anenhanced gap fill layer using the multi-step deposition and treatmentprocess to eliminate voids and seams in the dielectric material. Afterthe planarization process, the top surfaces of the poly gate structures604 and the STI structures 902 are coplanar.

FIG. 10 is an isometric view of a partially-fabricated semiconductorstructure after a gate replacement process according to an exemplaryembodiment of the present disclosure. Partially-fabricated semiconductorstructure 1000 includes the substrate 302, the fin structures 304, theseed layer structures 410, the conductive rails 502, thepartially-etched ILD 602, the STI structures 902, and metal gatestructures 1002.

As described above with reference to FIG. 6, although the poly gatestructures 604 are described as using polysilicon or amorphous silicon,the poly gate structures 604 can be sacrificial gate structures such asformed in a replacement gate process used to form metal gate structures.For example, the poly gate structures 604 can be replaced by metal gatestructures 1002 (also referred to as gate regions) as illustrated inFIG. 10. The metal gate structures 1002 can further include barrierlayer(s), gate dielectric layer(s), work function layer(s), fill metallayer(s), and/or other suitable materials for metal gate structures. Inan exemplary embodiment, the metal gate structures 1002 can includecapping layers, etch stop layers, and/or other suitable materials. Thegate replacement process can be a self-aligned gate replacement processwhere no alignment is needed. For example, the gate replacement processcan begin by removing the poly gate structures 604 through an etchingprocess such as, for example, a dry etching process, a wet etchingprocess, other suitable processes, and/or combinations thereof. Theremoval of the poly gate structures 604 leaves openings in thepartially-fabricated semiconductor structure 1000. Conductive materialused to form the metal gate structures 1002 can be then blanketdeposited over the openings. A subsequent planarization process can thenbe used such that the top surfaces of STI structures 902 and the metalgate structures 1002 are coplanar. After the planarization process, thedeposited metal gate material forms the metal gate structures 1002.Because the deposited metal gate material forms in the openings withoutthe need of alignment, the gate replacement process is a self-alignedprocess.

FIG. 11 is an isometric view of a partially-fabricated semiconductorstructure after forming metal source/drain contacts according to anexemplary embodiment of the present disclosure. Partially-fabricatedsemiconductor structure 1100 includes the substrate 302, the finstructures 304, the seed layer structures 410, the conductive rails 502,the partially-etched ILD 602, the metal gate structures 1002, etched STIstructures 1102, and source/drain contacts 1104.

In the exemplary embodiment illustrated in FIG. 11, the source/draincontacts 1104 can be metallic contacts that are formed directly on theepitaxial source/drain terminals 802 and used to provide electricalconnection to the epitaxial source/drain terminals 802. Patterning andetching processes can be used to form openings in the STI structures 902for the deposition of source/drain contact material. In an exemplaryembodiment, STI material can be removed from between opposing the metalgate structures 1002 to expose underlying the epitaxial source/drainterminals 802. In an exemplary embodiment, this STI material can remainbetween adjacent fin structures 304 to provide electrical isolation. Theetched STI structures 1102 are formed by patterning and etching the STImaterial to expose the underlying the epitaxial source/drain terminals802. In an exemplary embodiment, the source/drain contacts 1104 areformed by a blanket deposition using an ALD process, a CVD process, aPVD process, or a combination thereof. In an exemplary embodiment, thesource/drain contacts 1104 can be made of metal such as, for example,cobalt (Co), tungsten (W), copper (Cu), nickel (Ni), ruthenium (Ru), orother suitable materials. In an exemplary embodiment, a planarizationprocess (e.g., a CMP process) is performed to remove excessivesource/drain contact material of the source/drain contacts 1104 that areformed over the top surfaces of the STI structures 902 and the metalgate structures 1002. The source/drain contacts 1104 can be formed afterthe planarization process, and the top surfaces of the source/draincontacts 1104, the etched STI structures 1102, and the metal gatestructures 1002 are coplanar. In an exemplary embodiment, thesource/drain contacts 1104 can further include a barrier layer to avoiddiffusion of materials from the source/drain contacts 1104 into theetched STI structures 1102.

In an exemplary embodiment, forming the source/drain contacts 1104 canfurther include forming a silicide layer between the source/draincontacts 1104 and the epitaxial source/drain terminals 802. In anexemplary embodiment an etch process is performed to recess the topsurfaces of the epitaxial source/drain terminals 802 to form a flatsurface for the source/drain contacts. In an exemplary embodiment,recessing the epitaxial source/drain terminals 802 increases the contactarea between the source/drain contacts 1104 and the epitaxialsource/drain terminals 802 which can reduce contact resistance. In anexemplary embodiment, forming the silicide layer is performed by asilicidation process that includes depositing a metal layer, causing themetal to react with the epitaxy layers or the active tin structures, andremoving the un-reacted metal layer. In an exemplary embodiment, thesilicide layer can include cobalt silicide (CoSix), nickel silicide(NiSix), other suitable silicide layers, and/or combinations thereof.

In some embodiments, conductive rail structures formed in interlayerdielectric materials can be used to provide electrical connectionbetween multiple gate structures of finFET arrays. FIG. 12 is anisometric view of a partially-fabricated semiconductor structure afterdepositing metal gate material and forming source/drain contactsaccording to an exemplary embodiment of the present disclosure. Thepartially-fabricated semiconductor structure 1200 includes structuressimilar to the structures formed in FIGS. 3-9. For example, thepartially-fabricated semiconductor structure 1200 includes a substrate1202, fin structures 1204, partially-removed seed layer structures 1206,conductive rails 1208, partially-etched ILD 1210 and STI structures 1214that are similar to their respective structures in FIGS. 3-9. In anexemplary embodiment, the partially-fabricated semiconductor structure1300 can be formed after removing the poly gate structures 604 of FIG.9. In an exemplary embodiment, the removal process can be a self-alignedremoval process where no patterning process is needed. For example, theremoval process can have high etch selectivity of the poly gate materialover other exposed structures so a mask material is not needed to shieldthe other exposed structures. In an exemplary embodiment, exposedstructures other than the poly gate structures can be covered to providefurther protection from the removal process.

After the removal process (the poly gate material is completelyremoved), the underlying fin structures 1204 and partially-etched ILD1210 are exposed, and the conductive rails 1208 remain underpartially-etched ILD 1210. This operation can be similar to the etchingprocess as described in FIG. 6. Next, trenches are formed in selectiveopenings where poly gate material has been removed, and the formedtrenches are used to expose portions of one or more conductive rails1208 such that subsequent structures (e.g., gate electrodes) can formdirect electrical contact with the one or more conductive rails 1208. Inan exemplary embodiment, the trench forming process to expose selectedconductive rails 1208 can be similar to the trench forming processdescribed above with reference to FIG. 7. As illustrated in FIG. 12,portions of conductive rails 1208A and 1208B are exposed and directlyconnected to metal gate structures 1216. In an exemplary embodiment, thedeposition of conductive material and formation of metal gate structures1216 can be similar to the formation of the metal gate structures 1002as described above with reference to FIG. 10. In an exemplaryembodiment, other formation processes can be used. Because theconductive rails are formed within the ILD layer, they can electricallyconnect multiple metal gate structures without occupying additionaldevice space.

In the exemplary embodiment illustrated in FIG. 12, similar to formingthe source/drain contacts 1104 described above with reference to FIG.11, patterning and etching processes can be used to form openings in theSTI structures 1214 for the deposition of source/drain contact material.Next, the source/drain contacts 1218 can be formed directly on theepitaxial source/drain terminals to form source/drain regions. In anexemplary embodiment, portions of STI material can be removed frombetween opposing metal gate structures 1218 to expose the underlyingepitaxial source/drain terminals. In an exemplary embodiment, STImaterial remains between adjacent fins to provide electrical isolation.

FIGS. 13-15 are isometric views of partially-fabricated semiconductorstructures integrating self-aligned via structures and a backside powergrid with the partially-fabricated semiconductor structure 1200according to exemplary embodiments of the present disclosure. Thoseskilled in the relevant art(s) will recognize the integrated scheme canbe applied to semiconductor structures, such as the partially-fabricatedsemiconductor structure 1100 to provide some examples, without departingfrom the spirit and scope of the present disclosure.

FIG. 13 is an isometric view of a partially-fabricated semiconductorstructure including BEOL metal wires with self-aligned vias afterdepositing metal gate material(s) and forming source/drain contactsaccording to an exemplary embodiment of the present disclosure. Thepartially-fabricated semiconductor structure 1300 includes the substrate1202, the fin structures 1204, the partially-removed seed layerstructures 1206, the conductive rails 1208, the partially-etched ILD1210, the STI structures 1214, the metal gate structures 1216 and thesource/drain contacts 1218 as described in FIG. 12, and further includesa dielectric layer structure 1320, metal wires 1324 each extending in afirst direction, dielectric layers 1326 formed on the metal wires 1324,metal wires 1328 each extending in a second direction different from thefirst direction, and a dielectric layer structure 1330.

In the exemplary embodiment illustrated in FIG. 13, the dielectric layerstructure 1320 is formed on the STI structures 1214, the metal gatestructures 1216, and the source/drain contacts 1218. The metal wire 1324can be formed by etching the dielectric layer structure 1320 to create afirst trench and depositing conductive material(s) into the firsttrench, and the dielectric layer 1326 can be deposited over the metalwire 1324 to fill the first trench. Next, the dielectric layer structure1330 can be formed on the dielectric layer structure 1320 and thedielectric layers 1326.

By etching the dielectric layer structure 1330 to create a secondtrench, which expose a portion of the dielectric layer structure 1320and a portion of the dielectric layer 1326, and etching the exposedportion of the dielectric layers 1326 to expose the metal wire 1324, aconductive through via V1 can be created and arranged to electricallyconnect the metal wire 1324 and the metal wire 1328 after the conductivematerial(s) are filled into the second trench. In the presentembodiment, the conductive through via V1, also referred to asself-aligned vias, can be created based on the difference in etchselectivities between the dielectric layer structure 1320 and thedielectric layers 1326. By way of example but not limitation, after thesecond trench is created in the dielectric layer structure 1330 toexpose the portion of the dielectric layer structure 1320 and theportion of the dielectric layer 1326, the exposed portion of thedielectric layer 1326 can be selectively etched to expose a portion ofthe metal wire 1324, while the exposed portion of the dielectric layerstructure 1320 would not be etched. Hence, the resulting via is createdon the exposed portion of the metal wire 1324 and aligned with theexposed portion of the metal wire 1324. After the conductive material(s)are filled into the second trench, the conductive through via V1 and thecorresponding metal wire 1328, which is connected to the conductivethrough via V1, are formed accordingly. In some embodiments, theconductive through via V2 and the corresponding metal wire 1328 can beformed in a similar manner.

As such, a source/drain region including the source/drain contact 1218can be electrically connected to the metal wire 1328 through theconductive through vias V0 and V1. In some embodiments, it is possibleto create a conductive through via between the metal wire 1324 and agate region including the metal gate structure 1216, such that the gateregion can be electrically connected to the metal wire 1328 through theconductive through via, formed between the metal wire 1324 and the gateregion, and the conductive through via V1.

FIG. 14 is an isometric view of a partially-fabricated semiconductorstructure after forming BEOL metal wires with self-aligned viasaccording to an exemplary embodiment of the present disclosure. Thedifference between the partially-fabricated semiconductor structure 1400and the partially-fabricated semiconductor structure 1300 is that thepartially-fabricated semiconductor structure 1400 includes conductivestructures 1404, which can include conductive through-substrate via(s)such as a through-silicon via (TSV) and/or a trench-typethrough-substrate via (e.g. a through-silicon trench (TST)), penetratingthe substrate 1402. In some embodiments, the conductive structures 1404can be formed by etching the substrate 1402 from a backside of thesubstrate 1402 to create opening(s) to expose one or more conductiverails 1208, and filling conductive material(s) into the opening(s). Insome embodiments, the exposed one or more conductive rails 1208 cancontact source/drain region(s) and/or gate region(s).

By of example but not limitation, first of all, photoresist is formed onthe backside of the substrate 1402. Portions of the photoresist areexposed using a photo mask. Exposed or unexposed portions of thephotoresist are then removed, depending on whether a negative orpositive photoresist is used, to expose portions of the substrate 1402.Next, an etching process is performed to remove the exposed portions ofthe substrate 1402. In some embodiments, the etching process includes anRIE process using fluorocarbon gases such as CF₄, CHF₃, C₃F₈, othersuitable etchant gases, and/or combinations thereof, but the presentdisclosure is not limited thereto. The expose portions of the substrate1402 are etched from the backside to expose the one or more conductiverails 1208. Thereafter, the remaining photoresist was removed. In someembodiments, a plasma ashing or wet strip process is used to remove theremaining photoresist. In some embodiments, the plasma ashing process isfollowed by a wet dip in a sulfuric acid (H₂SO₄) solution to clean thebackside of the substrate 1402 and remove the remaining photoresist.

After the remaining photoresist is removed, deep trench structure(s), ordeep via structure(s), having opening(s) is formed from the backside ofthe substrate 1402 to expose the one or more conductive rails 1208 onthe front side of the substrate 1402. Next, conductive material(s), suchas Cu, Al, Ti, Ta, W, Nb, Mo, TiN, TiC, TaN, Ti/W or Ti/TiN, any otherknown conductive or semi-conductive materials, or combinations thereof,is filled into the opening(s) to form the conductive structures 1404. Asthe opening(s) of the deep trench/via structure(s) has sufficient crosssectional areas exposed to the front side of the substrate 1402, it iseasy to have the filled conductive material(s) coupled to the one ormore conductive rails 1208.

In some embodiments, bottom surfaces of the substrate 1402 and theconductive structures 1404 can be substantially coplanar by performingsuitable planarization processes on the bottom surfaces of thesestructures. The planarization process can be, for example, a CMPprocess. Additionally, or alternatively, a thickness of the substrate1402 can be less than that of the substrate 1302 shown in FIG. 13. Insome embodiments, the substrate 1302 shown in FIG. 13 can be groundusing a grinding process, such as a CMP process or other suitableprocesses, to form the substrate 1402 before the conductive structures1404 are formed. In these embodiments, after the substrate 1402 isground to reduce the thickness thereof, the ground substrate 1402 isetched from the backside to create opening(s) to expose the one or moreconductive rails 1208.

FIG. 15 is an isometric view of a partially-fabricated semiconductorstructure after integrating a backside power grid according to anexemplary embodiment of the present disclosure. The difference betweenthe partially-fabricated semiconductor structure 1500 and thepartially-fabricated semiconductor structure 1400 is that thepartially-fabricated semiconductor structure 1500 includes metal pads1522, power grid conductors 1524 and isolation structures 1526. Eachmetal pad 1522 can be situated between the substrate 1402 and acorresponding power grid conductor 1524 to provide electrical connectionbetween the power grid conductor 1524 and the conductive structure 1404in the substrate 1402. In some embodiments, the metal pads 1522, as wellas the power grid conductors 1524, can be a portion of a power grid. Insome embodiments, it is possible to directly connect the power gridconductors 1524 to the conductive structures 1404.

The metal pads 1522 can be formed using photolithography and etchingprocesses. For example, after the conductive structure 1404 is formed, aphotoresist can be formed over the backside of the substrate 1402.Portions of the photoresist are exposed using a photo mask. Exposed orunexposed portions of the photoresist are then removed, depending onwhether a negative or positive photoresist is used, to create opening(s)which is exposed to the conductive structures 1404. Next, conductivematerial(s), such as Cu, Al, Ti, Ta, W, Nb, Mo, TiN, TiC, TaN, Ti/W orTi/TiN, any other known conductive or semi-conductive materials, orcombinations thereof, is filled into the opening(s) to form the metalpads 1522. Thereafter, the remaining photoresist was removed. In someembodiments, a plasma ashing or wet strip process is used to remove theremaining photoresist. In some embodiments, the plasma ashing process isfollowed by a wet dip in a sulfuric acid (H₂SO₄) solution to clean thebackside of the substrate 1402 and remove the remaining photoresist.

It should be noted that the structure of the power grid conductors 1524are for illustrative purposes only, and is not intended to limit thescope of the present disclosure. In some embodiments, the power gridconductors 1524 may be arranged in different directions according todesign requirements. For example, the structure of the power gridconductors 1524 may include a parallel power rail structures to reduceIR (voltage) drops, wherein one of the power grid conductors 1524 (e.g.a lower power grid conductor) can be disposed in parallel with anotherof the power grid conductors 1524 (e.g. an upper power grid conductordisposed above the lower power grid conductor).

By integrating conductive structures, penetrating a semiconductorsubstrate, and the conductive rail structures, situated within adielectric region on a front side of the semiconductor substrate, into asemiconductor chip (or an integrated circuit), one or more power gridscan be disposed on a backside of the semiconductor substrate to provideelectrical power for circuit elements on the front side through theconductive structures (e.g. TSVs and/or TSTs) and the conductive railsstructures. In other words, as the conductive rails structures can beused for in-cell connection, such as electrical connection between atleast two conductive regions of gate region(s), drain region(s) andsource region(s), the circuit elements on the front side can be poweredby one or more backside power grids rather than front side power lines,thus saving routing resources on the front side. For example, one ormore metal wires, originally used as front side power lines, can be usedin other applications. Additionally, as the conductive rails structurescan be used for in-cell connection, the conductive structures need notto be so deep as to contact conductive regions on the front side, andthe conductive regions need not to have jog shapes for connecting theconductive structures.

By further integrating self-aligned via structures for connecting BEOLmetal wires on the first side, upper metal wires/layers can beself-aligned with lower metals/layers to reduce misalignments anddielectric breakdowns on a font side of a semiconductor device/chip (oran integrated circuit), such as time dependent dielectric breakdowns(TDDB). The interconnected network of conductive rails and conductivestructures can lessen the area in terms of real estate necessary to formthe one or more integrated circuits and also save an amount of routingresources used on the front side of the semiconductor chip.

FIG. 16 is a flow chart of an exemplary method for forming a non-planarsemiconductor device according to an exemplary embodiment of the presentdisclosure. Other operations in the method 1600 can be performed andoperations of the method 1600 can be performed in a different orderand/or vary.

At operation 1602, a fin structure is formed and protrudes from a frontside of a substrate of the non-planar semiconductor device. For example,as described in FIG. 3, the fin structures 304 are formed and protrudefrom a front side of the substrate 302.

At operation 1604, a dielectric region is formed on the front side ofthe substrate, wherein the dielectric region comprises a conductive railburied within the dielectric region and being in parallel with the finstructure. For example, as described in FIG. 5, the ILD 506 is formed onthe substrate 302, and one or more conductive rails 502 are buriedwithin the ILD 506 and parallel with the fin structures 304.

At operation 1606, a first opening is formed in the dielectric region toexpose the conductive rail. For example, as described in FIG. 7, thetrenches 702 are formed in the partially-etched ILD 602 to exposeportions of one or more of the conductive rails 502 that are formedbetween adjacent poly gate structures 604. In another example, asdescribed in FIG. 12, trenches are formed in the partially-etched ILD1210 to expose portions of one or more of the conductive rails 1208 suchas the conductive rails 1208A and 1208B.

At operation 1608, a plurality of conductive regions are formed on thedielectric region, wherein a first conductive region of the plurality ofconductive regions contacting the conductive rail through the firstopening. For example, as described in FIG. 7 and FIG. 8, the epitaxialsource/drain terminals 802 are formed on the partially-etched ILD 602,and the epitaxial source/drain terminals 802A and 802B of the epitaxialsource/drain terminals 802 connect to the conductive rail regions 502Aand 502B, respectively. In another example, as described in FIG. 12, thegate structures 1216 are formed on the partially-etched ILD 1210, andarranged to connect to the conductive rails 1208A and 1208B,respectively.

At operation 1610, the substrate is etched from a backside thereof toform a second opening to expose the conductive rail. For example, asdescribed in FIG. 14, the substrate 1402 is etched from a backside toexpose one or more conductive rails 1208. In some embodiments, beforeetching the substrate 1402 from the backside, a thickness of thesubstrate 1402 can be reduced (e.g. by wafer grinding) to facilitate theetch process.

At operation 1612, a first conductive material is filled into the secondopening to form a through-substrate via in the substrate. For example,as described in FIG. 14, conductive material(s) are filled into theopening(s) to form through-substrate vias penetrating the substrate1402.

In some embodiments, after one or more through-substrate vias are formedin the substrate, a power grid conductor can be connected to thebackside of the substrate to integrate a backside power scheme into thenon-planar semiconductor device. Additionally, or alternatively, a metalpad can be formed onto the backside of the substrate to electricallyconnect the power grid conductor to the through-substrate via. Forexample, as described in FIG. 15, one or more power grid conductors 1524of a power grid can be connected to the conductive structures 1404 (e.g.TSVs and/or TSTs). In some embodiments, as the conductive structures1404 (e.g. TSVs and/or TSTs) can be electrically connected to one ormore conductive rails 1208 which are electrically connected to one ormore conductive regions (e.g. source, gate and/or drain regions), theone or more power grid conductors 1524 can be electrically connected tothe one or more conductive regions on the front side of the substrate1402.

In some embodiments, the method 1600 can include operation(s) to formmetal wires with self-aligned vias on the front side of the substrate,such as the following operations: forming a dielectric layer on theplurality of conductive regions, the dielectric layer including a firstmetal wire extending in a first direction, the first metal wire beingburied within the dielectric layer and electrically connected to one ofthe plurality of conductive regions; forming a trench in the dielectriclayer to expose the first metal wire, the trench extending in a seconddirection different from the first direction; and depositing a secondconductive material into the trench to form a conductive through via anda second metal wire, wherein the first metal wire is electricallyconnected to the second metal wire through the conductive through via.

For example, as described in FIG. 13, a dielectric layer (including thedielectric layer structure 1320 and the dielectric layers 1326) can beformed on the metal gate structures 1216 and the source/drain contacts1218 (a plurality of conductive regions), wherein one or more metalwires 1324 are buried within the dielectric layer and extend in a firstdirection. The one or more metal wires 1324 can be electricallyconnected to conductive region(s). In the exemplary embodimentillustrated in FIG. 13, the metal wire 1324 can be electricallyconnected to a gate region including the metal gate structure 1216through the conductive through via V0. Next, a trench can be formed inthe dielectric layer to expose the metal wire 1324, wherein the trenchextends in a second direction different from the first direction suchthat the metal wire 1324 and the dielectric layer structure 1320 areexposed. Conductive material(s) can be deposited into the trench to forma conductive through via and a metal wire, wherein the metal wire 1324is electrically connected to the formed metal wire through theconductive through via. For example, in the exemplary embodimentillustrated in FIG. 13, one metal wire 1324 can be electricallyconnected to one metal wire 1328 through the conductive through via V1,and another metal wire 1324 can be electrically connected to anothermetal wire 1328 through the conductive through via V2.

Some embodiments described herein may include a semiconductor devicethat includes a substrate, a dielectric region, a plurality ofconductive regions, a first conductive rail and a conductive structure.The dielectric region is situated on the substrate. The plurality ofconductive regions are situated on the dielectric region. The firstconductive rail is situated within the dielectric region, and iselectrically connected to a first conductive region of the plurality ofconductive regions. The conductive structure is arranged to penetratethrough the substrate and formed under the first conductive rail. Theconductive structure is electrically connected to the first conductiverail.

Some embodiments described herein may include an integrated circuit thatincludes a substrate, a dielectric region, a first fin field-effecttransistor, a conductive rail and a conductive structure. The dielectricregion is situated on the substrate. The first fin field-effecttransistor includes a first source region, a first gate region and afirst drain region situated on the dielectric region. The conductiverail is situated within the dielectric region, and is electricallyconnected to a first terminal region selected from among the firstsource region, the first gate region and the first drain region. Theconductive structure is arranged to penetrate through the substrate andformed under the conductive rail. The conductive structure iselectrically connected to the conductive rail.

Some embodiments described herein may include a method for forming anon-planar semiconductor device that includes forming a fin structureprotruding from a front side of a substrate of the non-planarsemiconductor device and forming a dielectric region on the front sideof the substrate. The dielectric region includes a conductive rail whichis buried within the dielectric region and in parallel with the finstructure. The method may further include forming a first opening in thedielectric region to expose the conductive rail, forming a plurality ofconductive regions on the dielectric region, wherein one of theplurality of conductive regions contacts the conductive rail through thefirst opening. The method may further include etching the substrate froma backside of the substrate to form a second opening to expose theconductive rail, and filling a first conductive material into the secondopening to form a through-substrate via in the substrate.

The foregoing outlines features of several embodiments so that thoseskilled in the art may better understand the aspects of the presentdisclosure. Those skilled in the art should appreciate that they mayreadily use the present disclosure as a basis for designing or modifyingother processes and structures for carrying out the same purposes and/orachieving the same advantages of the embodiments introduced herein.Those skilled in the art should also realize that such equivalentconstructions do not depart from the spirit and scope of the presentdisclosure, and that they may make various changes, substitutions, andalterations herein without departing from the spirit and scope of thepresent disclosure.

What is claimed is:
 1. A semiconductor device, comprising: a substrate;a dielectric region situated on the substrate; a plurality of conductiveregions situated on the dielectric region; a first conductive railsituated within the dielectric region, the first conductive rail beingelectrically connected to a first conductive region of the plurality ofconductive regions, wherein the first conductive region contacts a topsurface of the first conductive rail at a level where the firstconductive region contacts a top surface of the dielectric region; and aconductive structure penetrating through the substrate and formed underthe first conductive rail, the conductive structure being electricallyconnected to the first conductive rail.
 2. The semiconductor device ofclaim 1, the conductive structure comprises a conductivethrough-substrate via.
 3. The semiconductor device of claim 1, furthercomprising: a power grid conductor situated under the substrate, thepower grid conductor being electrically connected to the conductivestructure.
 4. The semiconductor device of claim 3, further comprising: ametal pad situated between the substrate and the power grid conductor,the metal pad configured to electrically connect the power gridconductor to the substrate.
 5. The semiconductor device of claim 1,further comprising: a fin structure protruding from the substrate andthe dielectric region and contacting the conductive structure.
 6. Thesemiconductor device of claim 5, further comprising: a second conductiverail situated within the dielectric region and electrically connected tothe conductive structure, wherein the first conductive rail faces afirst sidewall of the fin structure, and the second conductive railfaces a second sidewall of the fin structure.
 7. The semiconductordevice of claim 5, wherein the plurality of conductive regions comprisesa source region, a gate region and a drain region, and the finstructure, the source region, the gate region and the drain region areconfigured to form a fin field-effect transistor.
 8. The semiconductordevice of claim 1, further comprising: a first metal wire electricallyconnected to a second conductive region of the plurality of conductiveregions, the first metal wire extending in a first direction; a secondmetal wire extending in a second direction different from the firstdirection; and a conductive through via located on the first metal wireand below the second metal wire, the first metal wire being electricallyconnected to the second metal wire through the conductive through via.9. The semiconductor device of claim 8, wherein the second conductiveregion is electrically connected to the first conductive region throughthe first conductive rail, or is isolated from the first conductive railby the dielectric region.
 10. An integrated circuit, comprising: asubstrate; a dielectric region situated on the substrate; a first finfield-effect transistor, comprising a first source region, a first gateregion and a first drain region situated on the dielectric region; aconductive rail situated within the dielectric region, the conductiverail being electrically connected to a first terminal region selectedfrom among the first source region, the first gate region and the firstdrain region, wherein the first terminal region electrically connectedto the conductive rail contacts each of respective portions of thedielectric region located on opposite sides of the conductive rail; anda conductive structure penetrating through the substrate and formedunder the conductive rail, the conductive structure being electricallyconnected to the conductive rail.
 11. The integrated circuit of claim10, wherein the first fin field-effect transistor further comprises afin structure protruding from the substrate and the dielectric regionand contacting the conductive structure.
 12. The integrated circuit ofclaim 10, the conductive structure comprises a conductivethrough-substrate via.
 13. The integrated circuit of claim 10, furthercomprising: a power grid conductor situated under the substrate, thepower grid conductor being electrically connected to the conductivestructure.
 14. The integrated circuit of claim 13, further comprising: ametal pad situated between the substrate and the power grid conductor,the metal pad configured to electrically connect the power gridconductor to the substrate.
 15. The integrated circuit of claim 10,further comprising: a second fin field-effect transistor, comprising asecond source region, a second gate region and a second drain regionsituated on the dielectric region; and a first metal wire electricallyconnected to a second conductive region selected from among the firstsource region, the first gate region, the first drain region, the secondsource region, the second gate region and the second drain region, thefirst metal wire extending in a first direction; a second metal wireextending in a second direction different from the first direction; anda conductive through via located on the first metal wire and below thesecond metal wire, the first metal wire being electrically connected tothe second metal wire through the conductive through via.
 16. Asemiconductor device, comprising: a substrate; a dielectric regionsituated on the substrate; a fin structure protruding from the substrateand the dielectric region; a conductive rail situated within thedielectric region, the conductive rail facing a sidewall of the finstructure, wherein a bottom surface of the conductive rail is at a levelequal to or higher than a bottom surface of a fin of the fin structure;and a conductive structure penetrating through the substrate and formedunder the conductive rail, the conductive structure being electricallyconnected to the conductive rail.
 17. The semiconductor device of claim16, further comprising: a power grid conductor situated under thesubstrate, the power grid conductor being electrically connected to theconductive rail through the conductive structure.
 18. The semiconductordevice of claim 16, further comprising: a conductive region situated onthe dielectric region and electrically connected to the conductive rail.19. The semiconductor device of claim 16, further comprising: aconductive region situated on the dielectric region, the conductiveregion being isolated from the conductive rail by the dielectric region.20. The semiconductor device of claim 16, wherein the conductivestructure is further formed under the fin structure, and electricallyconnected to the fin structure.